Pipe wrapping material



United States Patent 3,219,064 PIPE WRAPPING MATERIAL Raymond E. Downey, West Haven, Conn., assignor to The Seamless Rubber Company, New Haven, Conn., a corporation of Connecticut N0 Drawing. Filed Sept. 14, 1961, Ser. No. 137,998 19 Claims. (Cl. 138-145) This application is a continuation-in-part of copending US. Patent application Serial No. 99,051 filed March 29, 1961, and now abandoned.

The present invention relates to new and improved 1 compositions for protective wrappings and to a method for producing the same.

More particularly, the present invention relates to the protection of metallic or other articles subject to oxidation, corrosion, or deterioration, and is especially concerned with the preparation and utilization of a tape shielding material for protecting pipe-lines either above ground, where they may be exposed to atmospheric oxidation or corrosion, or under ground where they may be subjected to the action of corrosive sub-surface waters, electrolysis, soil stresses and other injurious agencies.

Many previous attempts have been made to solve these problems by employing various types of pipe wrappings. These pipe wrapping compositions, however, while providing a considerable degree of protection have not proven to be entirely satisfactory because of poor abrasion resistance, brittleness, high manufacturing cost and diffculties encountered in application.

It is an object of the present invention to provide a flexible, abrasion resistant, and inexpensive unsupported pipe wrap tape which can be readily manufactured and easily applied. Another object is to provide a method for producing such a pipe wrap tape. Still another object is to provide a method for applying the protective pipe wrapping componnd of the preesnt invention to pipes. A further object is to provide pipe wrap tapes having excellent resistance to hydrocarbons. A still further object is to provide a weather-resistant, abrasion resistant covering for various surfaces. These and other objects of the present invention will become apparent as the description proceeds.

It has now been found that a self-supporting flexible protective wrap having a high tensile strength and high resistance to abrasion may be formed from a fused vinyl resin, plasticizer and tar pitch. More particularly this new and improved pipe wrap tape for the protection of sui'faces from corrosion can be prepared from tape-forming compositions containing from about 15% to about 50% tar pitch, from about 30% to about 60% polyvinyl chloride or copolymers thereof, and from about to about 25% polyvinyl chloride plasticizer.

Tar pitch is a heavy liquid or dark residue obtained by distillation of tar. It forms a lustrous brittle mass when cold, and a semi-solid to syrupy mass according to the degree of heat to which it is subjected. It consists of many organic compounds which differ according to their origin. While coal tar pitch is preferred, the tar pitch may be obtained from various other sources such as wood, peat, shale or other vegetable or mineral materials. Filled or unfilled tar pitches or bituminous enamels are suitable. As examples of fillers there may be mentioned talc, whiting and silica. A commercially available unfilled pitch is #7 pitch (Koppers Co.) while 70B enamel (Koppers Co.) is a commercially available filled enamel.

It has been found that polyvinyl chloride or copolymers thereof form suitable thermoplastic binders or vehicles for the coal tar in that they are characterized by exceptionally high toughness and resistance to abrasion without undesirable brittleness, and in addition, in their fused state they serve effectively to prevent volatilization of the coal tar.

. position.

3,219,064 Patented Nov. 23, 1965 The particular polyvinyl chloride resin employed will be determined by the end use for the article which it is to cover. Generally, a straight polyvinyl chloride resin of medium molecular weight is preferred for calendering or extruding. However, a high molecular weight resin is best for plastisols and organosols. Specific examples of suitable polyvinyl chloride resins include Vygen #110, made by General Tire and Rubber Co., Geon #103 and #121 made by Goodrich Chemical Co., and VR-24 and VR-50, made by Naugatuck Chemical Division, US. Rubber Co.

The plasticizer is added to impart additional flexibility to the polyvinyl chloride. The choice of the specific plasticizer, or mixture of plasticizers, to be employed will be made by those familiar with polyvinyl chloride resins depending upon the physical properties desired in the final product. A preferred plasticizer is tetrahydrofurfuryloleate sold under the trade name Plastolein #9250 by Emery Industries, Inc.

While the pipe wrap tapes of the present invention may be reinforced with various materials, or impregnated thereinto, such reinforcement or impregnation while necessary for conventional tar coatings is not necessary or preferred in achieving the objects of the present invention. Very high tensile strengths are obtained with unsupported pipe wrap compositions prepared in accordance with the present invention.

The new pipe wrap tapes of the present invention can be made by extruding, calendering, or casting. For example, the coal tar, polyvinyl chloride and plasticizer composition can be mixed in a ribbon blender or a Hobart or a Banbury type mixer, and the resulting dry blend extruded or calendered into sheet form. The mixing can also be accomplished by feeding the composition through a roll mill. Preferably, the mixing should be carried out at temperatures over about 200 F. and calendering should be carried out at temperatures over about 25 0 F. to about 350 F. The composition can be fused during the mixing operation, during the calendering operation or when in sheet form by subjecting the composition to a temperature above the fusion temperature, that is, between about 250 F. and about 350 F. depending on the particular com- The fusion step which provides for the solution of the vinyl resin in the plasticizer is hereinafter characterized as the formation of a condensed product which provides an extremely durable inert composition having a high modulus,* excellent abrasion resistance, high tensile strength and better high temperatures properties than conventional tar coatings.

By proper choice of polyvinyl chloride resin, either a plastisol or organosol system can be prepared in which the sheet material can be cast on release paper in a liquid state, then gelled and fused. VR-24 is an example of a resin satisfactory for calendering, and VR-SO and Geon 121 are suitable for plastisol or organosol formulations used in making castings.

The solvents to be employed in the organosol formulations will be apparent to those familiar with polyvinyl chloride organosols. Solvesso and V.M. & P. naphtha may be mentioned, however, as specific examples of such solvents, it being understood that the choice of solvents is not intended to be limited to the examples given.

One of the advantages of the present pipe wrap tapes is that they do not require a pressure-sensitive adhesive for bonding to a pipe or other article to be protected. Unlike pipe wrap tapes having a polyethylene backing which require the use of an adhesive, the pipe or other article to be protected can be coated with a primer containing a solvent for the vinyl chloride such as methylf As defined in the Vanderbilt Rubber Handbook.

ethylketone, and the wrap thereby suitably bonded to the article to be protected. An example of such a primer is Roystons B616, 21 cosolvent system of vinyl polymers, made by Roystons Laboratories, Inc.

The pipe wrap tapes of the present invention can, of course, be coated with an adhesive, if desired. The adhesive can be, for example, a pressure-sensitive adhesive. A suitable composition for a pressure-sensitive adhesive usable within the scope of the present invention is as follows:

4 placed in hydrocarbon saturated ground. While the pipe wrap tapes of the present invention have sufiicient coldflow characteristics to provide good bonding to the article being coated, they are essentially non cold-flowing and, hence, will have little tendency toward separation due to stresses encountered under actual use. Because these tapes have better high temperature properties than conventional tar coatings, they are suitable for coating pipes downstream from compressors. Due to the fused condition of the tapes of the present invention there is no Parts by weight need for an inner liner to prevent blocking or self ad- Natural rubber 38 hesion.

Filler: Typical formulations for the compositions of the pres- Zinc oxide 2 ut invention Will now be given. All parts are to be Hydrated alumina 30 understood as expressed in parts by weight,

Carbon black 3 Examples of calendering formulations are as follows:

Resins:

Pentalyn H 25 Parts Polypale ester No, 1 Ingredwnts SP-12 4 20 I 11 III IV 122 #7 Coal tar pitch 40 20 50 so via-24 Resin 40 so 40 30 Pentalyn H is a pentaerythritol ester of hydrogenated #9250 Plastieizer 20 2o 10 20 rosin, Polypale ester No. 1 is a polyethylene glycol ester 25 Total 100 100 100 100 of polymerized rosin, both of which are manufactured by the .Hercuies Powder wllimngton Delaware i Examples V, VI and VII give plastisol formulations SP 12 is an oil-soluble, heat reactive, unmodified phenolic which were found Suitable for casting While examples resin manufactured by Schenectady Varmsh VIII, IX and X give organosol formulations which were Schenectady New York found suitable for casting.

The adhesive mass is prepared by milling natural rubber until it is smooth and uniform. The fillers are then added and milling is continued until the mixture is also smooth and uniform. The resins are then added to the mixture for proper tackiness and the milling is continued until the entire batch is a homogeneous blend. When a pressure-sensitive adhesive of the above type is used plasticizer NP-lO, Eastman Chemical Company (a terminated polyester of neopentylg1ycol-2,Z-dimethyl-1,3-propanediol and adipic acid) may be substituted for plasticizer #9250 in the vinyl-coal tar type of compound.

The pipe wrap tapes of the present invention have a very high abrasion, impact and scuff resistance, while maintaining a high degree of flexibility, a tensile strength of from about 1600 to about 2500 p.s.i., and an elongation of about 150 to about 200%. The abrasion resistance of these protective tapes is much higher than that of the laminated pipe wraps currently available. This combination of high tensile strength with high degree of flexibility and elongation was entirely unobvious and unexpected. The pipe wrap tapes of the present invention are homogeneous blends rather than laminations, and are more easily manufactured than laminations. The polyethylene backing frequently used in laminated pipe wraps is of a fragile nature and more easily damaged by abrasion and scuffing. This has necessitated the prevalent practice of using overwraps on the pipe. The pipe wrap tapes of the present invention do not have to be so protected and afford excellent corrosion protection at a very low cost.

In addition, the pitch-filled vinyl pipe wrap tapes of the present invention lend themselves to application at the mill as well as in the field as they are much heavier and tougher than laminated pipe wrap material. When applied over a Wet prime coating, there will be less tendency for the present pipe wrap tapes to blister, such as is likely to occur with laminated pipe wrap tapes. The excellent hydrocarbon resistance of these pipe wrap tapes is of critical importance for applications to pipes to be used to transport hydrocarbons, as otherwise a leak in the pipe would cause removal of the pipe wrap for up to a hundred feet or more in both directions from the leak, thus necessitating removal and recovering of a large section of pipe. In addition, this excellent hydrocarbon resistance makes the pipe wrap tapes of the present invention particularly suitable for application to pipes The compositions of the present invention are not limited to their use in tape or sheet form, but may also be formed in situ, as for example in covering roofs and floors.

Various modifications and changes other than those set forth herein may be made in the composition and process of this invention without departing from the sprit thereof, and accordingly it will be understood that the invention is to be limited only within the scope of the appended claims.

I claim:

1. A protected pipe line comprising a conduit having a coating of a high tensile strength fused pipe wrap tape comprising a condensed product of from about 15% to about 50% tar pitch, from about 30% to about 60% of a member selected from the group consisting of polyvinyl chloride and its copolymers, and from about 10% to about 25% polyvinyl chloride plasticizer.

2. A protected pipe line according to claim 1 wherein the pitch is obtained from coal tar and the plasticizer is tetrahydrofurfuryloleate.

3. A high tensile strength fused protective pipe wrap tape capable of being bonded without an adhesive to a pipe which comprises a condensed product of a blend of about 15% to about 45% coal tar pitch, about 30% to about 60% of a member selected from the group consisting of polyvinyl chloride and its copolymers, and from about 10% to about 25% plasticizer.

4. A protected pipe line comprising a conduit having a coating of a self-supporting flexible protective wrap bonded thereon Without an adhesive which comprises a condensed product of a blend of a fused vinyl resin, a plasticizer and about 15% to about 45% coal tar pitch.

5. A self-supporting flexible protective wrap having a high tensile strength in the range of from 1600 p.s.i. to 2500 p.s.i., an elongation of at least and high resistance to abrasion comprising a condensed product of a fused vinyl resin, plasticizer and about 15% to about 45% tar pitch.

6. A high tensile strength fused, flexible, pipe wrap tape comprising a blend consisting essentially of a condensed product of from about 15 to less than 50% tar pitch, from about 30% to about 60% of a member selected from the group consisting of polyvinyl chloride and its copolymers, and from about to about 25% plasticizer, all by weight, said pit-oh, plasticizer and member being completely fused together to form a homogeneous blend, said pipe wrap tape having a high tensile strength in the range of from 1600 p.s.i. to 2500'p.s.i., an

elongation of at least 150% and high resistance to abra-' 7. A high tensile strength fused, flexible pipe wrapping tape comprising a blend consisting essentially of a condensed product of 40 parts tar pitch, 40 parts polyvinyl chloride, and 20 parts plasticizer, all by weight, said pitch, plasticizer and polyvinyl chloride being completely fused together to form a homogeneous blend, said pipe wrapping tape having a high tensile strength in the range of from 1600 psi. to 2500 p.s.i., an elongation of at least 150% and high resistance to abrasion.

8. A high tensile strength fused, flexible pipe wrapping tape comprising a blend consisting essentially of a condensed product of 20 parts tar pitch, 60 parts poly vinyl chloride, and 20 parts plasticizer, all by weight, said pitch, plasticizer and polyvinyl chloride being completely fused together to form a homogeneous blend, said pipe wrapping tape having a high tensile strength in the range of from 1600 p.s.i. to 2500 p.s.i., an elongation of at least 150% and high resistance to abrasion.

9. A high tensile strength fused, flexible pipe wrapping tape comprising a blend consisting essentially of a condensed product of 50 parts tarpitch, 40 parts polyvinyl chloride, and 10 parts plasticizer, all by weight, said pitch, plasticizer and polyvinyl chloride being completely fused together to form a homogeneous blend, said pipe wrapping tape having a high tensile strength in the range of from 1600 p.s.i. to 2500 p.s.i., an elongation of at least 150% and high resistance to abrasion.

10. A high tensile strength fused, flexible pipe wrapping tape comprising a blend consisting essentially of a condensed product of 50 parts tar pitch, 30 parts polyvinyl chloride, and 20 parts plasticizer, all by weight, said pitch, plasticizer and polyvinyl chloride being completely fused together to form a homogeneous blend, said pipe wrapping tape having a high tensile strength in the range of from 1600 p.s.i. to 2500 p.s.i., an elongation of at least 150% and high resistance to abrasion.

11. A high tensile strength flexible pipe wrap tape comprising a fused homogeneous blend consisting essentially of a condensed product of 100 to 160 parts by weight of a plastisol containing 60 to 80% of a member from the group consisting of polyvinyl chloride and its copolymers and the remainder plasticizer, and 30 to 100 parts by weight tar pitch, said pipe wrap tape having a high tensile strength in the range of from 1600 p.s.i. to 2500 p.s.i., an elongation of at least 150% and high resistance to abrasion.

12. A high tensile strength fused protective pipe wrap tape capable of being bonded to a pipe in the absence of a pressure-sensitive adhesive which comprises a blend of a condensed product of about 15 to about 45 coal tar pitch, about 30% to about of a member selected from the group consisting of polyvinyl chloride and its co polymers and from about 10% to about 25% plasticizer.

13. A protected conduit having a coating of a high tensile strength fused pipe wrap tape comprising a condensed product of from about 15% to about 50% tar pitch, from about 30% to about 60% of a member selected from the group consisting of polyvinyl chloride and its copolymers and from about 10% to about 25 polyvinyl chloride plasticizer.

14. An unsupported flexible wrap for a pipeline having a high tensile strength in the range of from 1600 p.s.i. to 2500 p.s.i., an elongation of at least and high resistance to abrasion comprising a fused condensed product of homogeneous blend of about 15% to about 50% tar pitch, from about 30% to about 60% of a member selected from the group consisting of polyvinyl chloride and its copolymers and from about 10% to about 25% polyvinyl chloride plasticizer.

15. The wrap according to claim 14 in which the tar pitch is #7 coal tar pitch.

16. A protected conduit having a protective coating of a wrap comprising a fused condensed product of vinyl resin, plasticizer and about 15 to about 45% tar pitch.

17. A protected pipe line comprising a conduit having a fused coating comprising a condensed product of from about 15% to about 50% tar pitch, from about 30% to about 60% of a member selected from the group consisting of polyvinyl chloride and its copolymers, and from about 10% to about 25% polyvinyl chloride plasticizer.

18. A high tensile strength fused protective covering material capable of being bonded to a member in the absence of a pressure-sensitive adhesive which comprises a condensed product of a blend of about 15% to about 45 coal tar pitch, about 30% to about 50% of a member selected from a group consisting of polyvinyl chloride and its copolymers, and from about 10% to about 25 plasticizer.

19. A protective conduit having a covering of a high tensile strength fused coating comprising a condensed product of from about 15% to about 50% tar pitch, from about 30% to about 60% of a member selected from a group consising of polyvinyl chloride and its copoly; mers, and from about 10% to about 25 polyvinyl chloride plasticizer.

References Cited by the Examiner UNITED STATES PATENTS 2,635,085 4/ 1953 Gonnard et al 26028.5 2,801,945 8/1957 Rogers 138-146 X 2,883,354 4/1959 Sperling 260-28,5 2,918,940 12/1959 Carr 156187 2,937,665 5/1960 Kennedy 138145 3,033,724 5/1962 Stokes 156187 FOREIGN PATENTS 581,368 10/ 1946 Great Britain.

722,505 1/ 1955 Great Britain.

726,816 3/1955 Great Britain.

LEWIS J. LENNY, Primary Examiner.

EDWARD V. BENHAM, Examiner. 

5. A SELF-SUPPORTING FLEXIBLE PROTECTIVE WRAP HAVING A HIGH TENSILE STRENGTH IN THE RANGE OF FROM 1600 P.S.I. TO 2500 P.S.I., AN ELONGATION OF AT LEAST 150% AND HIGH RESISTANCE TO ABRASION COMPRISING A CONDENSED PRODUCT OF A FUSED VINYL RESIN, PLASTICIZER AND ABOUT 15% TO ABOUT 45% TAR PITCH.
 16. A PROTECTED CONDUIT HAVING A PROTECTIVE COATING OF A WRAP COMPRISING A FUSED CONDENSED PRODUCT OF VINYL RESIN, PLASTICIZER AND ABOUT 15% TO ABOUT 45% TAR PITCH. 